Gear checking device



July 27, 1937. H. PELPHREY GEAR CHE`CKING DEVICE Filed Dec. 4, 1953 2 sheets-sheet@ INVENTOR v Hdl/ffy Pelprery /JLA MQ/'M ORNEYS.

July 27, 1937. l HQ PELPHREY l 2,087,957

GEAR CHECKING DEVICE Filed Deo. 4, 1953 2 sheetsfsheet'z Illllllllllllllllll.

AT O'RNEY.

Patented '.iuiy 27, 1937 an 's gems? GEAR comme nevica Application December 4, 1933, Serial No. 700,785

9 Claims.

My invention relates to a device for testing the involute form of gear teeth and particularly to a l machine which willV accurately check the involute form of teeth of gears, worms, worm wheels and the like.

Heretofore it has been difficult to accurately check the involute form of teeth of gears because ofthe peculiar nature of the form, being that described by a point on a line as the line is tilted along the arc of a circle. To attain accuracy in the device applicant has eliminated all back lash and play between the parts which move in syn- 1 chronism and rotate the gear and move the in dicating device to eiect the accurate checking. This is eifected by employing a sine-bar to move the carriage which supports the indicating device, the means for moving. the sine-bar also rotating the gear to be checked in synchronism with the movement of the indicating device. It is, therefore, only necessary to move the support for the sine-bar to actuate the entire device to accurately check the involute form of the gear teeth.

Accordingly, the main objects of my invention are: to provide a checking device having a movable table which eects the rotation of the gear and the movement of the indicating device in synchronism with each other; to provide a movable table with a sine-bar for moving the carriage supporting the indicating device across the gear at the time the gear is rotated by the sine-bar support; to mount a gear .to be tested on a master base circle which is rotated by the movement of a device which effects the movement of an indicating device in synchronism with the rotation of the base circle of the gear; to provide an indicating device for checking the involute form which may be adjusted at any angle conforming to the helix angle of a gear to be tested, or the angle of thread of a worm, so that the involute form can be checked along anormal to the axis of the thread or tooth; and, in general, to provide an involute checking device which is simple in construction, positivein operation and-accurate in recording the tooth form.

Other objects and features of novelty of my invention will be either specically pointed out or will become apparent when referring, for a. better understanding of my inventioxnto the following description taken in conjunction with the accom- Panying drawings. wherein:

Figure 1 is a broken view in. elevation of a Fig. 2 is an enlarged broken view of the masterture illustrated in Fig. Staken on the line @-4 thereof, and

Fig. 5 is a sectional view of the structure illustrated in Fig. 4, taken on the line 5-5 thereof.

In the present invention, I employ a master 10 base circle for rotating a gear to be ltested and employ atable for operating the master circle. An indicating device is supported on. a carriage which is actuated by the table to move the device in synchronism with the movement of the gear. 15 The table has a sine-bar thereon-which may be adjusted so that the ratio between the movement of the table and carriage is in direct proportion to the ratio between the master circle and the base circle'l of the gear to'be tested. It is, there- 2o fore, only necessary to adjust ,the sine-bai'. to produce amovement of the carriage in ',proportion to the ratio between -the base circle of the gear and the master base circle to set the machine to test any size of gear. f

Referring to Figs. 1, 2 and 3 I haveillustrate the machine as comprising a base Il) having an upwardly projecting column vII carrying an adjustable center I2. Ways I3 are provided on one end of the frame I0 upon which a table l5 is 30 movable, being actuated in the usual manner by a lead screw, not shown, operated by a hand wheel I4. 'I'he back lashv between the driving of the lead screw `by the hand wheel Ill and the table I5 is preferably eliminatedV so that 35 the scale I6 may be employed for positioning the table. However, if any back lashdoes appear ln ,the'lead screw operated by the hand wheel Il,

this will in no way affect the accurate operation Aof the device. The tableA I5 has arcuate ways I'I 40 thereon by whicha sine-bar I8 is mounted, being secured thereon by bolts I9 in such manner that the sine-bar may be adjusted angularly upon the table I 5. The table I5 also carries a bar 2| which is pressed against4 an element22 defining a por- 45 V tion of a master base circle, the center of which is' aligned with the center 23 oftheadjustable center head I2.

Apair oi' ways 20 is provided on the base I0 perpendicular to the ways I3 upon 'which a car- 50 rlage 24 is mounted for movementy at iight angles 1 to the table I5. The carriage is provided with a y driving head 25 preferably having ahardened end 26 which contacts with the side of the sine-bar I8 when biased by a spring 50 toward the sine-bar. 55

In this manner, the carriage 24 is always urged toward the sine-bar and is retained with the end 26 in contact therewith. Through the movement of the table I5, the carriage 24 is moved a proportional amount depending upon the angular position of the sine-bar I8. vA slide 21 is provided on the carriage 24 movable parallel 'with the carriage and a slide 28 is mounted on the slide 21 for'movement at right angles to the carrlage 24. A lead screw 30 actuates the slideV 21v while a. lead screw 29 is employed to position the slide- 28 operated by a hand wheel 3|. An upwardly projecting post 32 forms a portionof the slide 28 upon which arf indicating device 33 is mounted. A T shaped groove 34 is provided in the post 32 in which the head of a bolt 35 registers and which extends laterally through the indicating device 33 engaged by a clamping handle 86 by which the indicating device is secured in height relative to the post 32. By shifting the slides 21 and 28 the indicating device may be positioned relative to a tooth of a gear to be tested.

In referring to Figs. 4 and 5, I have illustrated the indicating device as having a stylus 40 mounted in a set of trunnions 31 which are pivoted on bearings 38 mounted in the bearing seats 4| which are retained in adjusted position by the set screws 42; The stylus 40 has a shoulder 43 thereon and is 'locked in place relative to the trunnions by a collarv 44. In this manner the stylus 48 may be turned in any position to have a protruding end thereof project in any desirable direction. The trunnions 31 are positioned medially of the ends of the stylus which terminates in a cylindrical iinger 45 which engages a slot 48 in an arm 4 1 which is mounted on a shaft 48.` The shaft is secured on the ball bearings 48 one of which is journaled in the bearing seat 5|, the other of which is positioned in the threaded bearing seat 52 and locked therein by a set screw 53. A bar 54 is mounted on the shaft 48 extending either side thereof to engage the stem of the indicatingdevices'55 mounted on a projecting boss 58 on the top of the device. It will be noted that the entire device is mounted in` a cylindrical housing 51 which is retained in the shouldered block 58 for the purpose of having the entire device rotatable relative to the supporting block 58. The entire device may be rotatedv to have the stylus 4|! traverse a spiral thread in accordance with the lead angle of the thread, so that the device may check helical gears as well as the bearing race 64 presses against the bar 2| on the side opposite to the element 22 and-is mounted on an eccentric support 85 which may be ad,- justed to urge the bar toward the master base circle. I'he center of the bar may be slotted and provided with a. frictional material 88 which will be forced against the arcuate surface of the element 22 and prevent any slippagel occurring therebetween. l When the eccentric support 65 is adjusted to move the bar inwardly, the screw 81 on Athe: opposite end of the bar may` be adjusted to retain the bar in parallel relation to,

the direction of movement of the table I5.

A driving plate 81 is mounted on top of the elefment 22 having a projecting lug 88 which operates a dog 68 mounted on the shaft 1| upon which a gear 12 to be tested is mounted. A clamping screw 13 is secured to the driving plate 81 for securing the plate to the master base circle to be operated therewith.l The screw 13 may be loosened so thatthe gear may-be indexed to have another tooth brought into engagement with the stylus 40 on the base circle of the gear with sumcient force to deflect the hand of one of the instruments 55. The nut 13 is thenv tightened to lock the driving plate 61 to the element 22.

In the operation of the machine, the gear 12 is secured to the shaft 1| and mounted between the centers 23 and 10 with the dog 69 in engagement with the driving pin 68 on the driving head 61. V'Ihe sine-bar is set* at such an angle, as pointed out hereinabove, as to move the carriage 24 relative to the movement ofthe table I5 in accordance with the ratio between the base circle of the gear 12 to be tested and vthe master base circle defined by ythe element 22. 'The driving head 81 is adjusted to have the tooth .to be tested in engagement with the stylus 40 directly on the base circle of the gear through the oper' ation of the slides 21 and 28. th'en tightened to clamp the driving head 81 relative to the element 22 and the indicating device 55 isthen-set to zero reading. The hand wheel |4 is then operated to drive the table |5 which rotates the element 22 and, therefore, the gear 12 and` also moves the carriage 24 to move the indicating device relative to the speed of rotation of the gear. The stylus 40 will follow the`rotation of the tooth as the gear rotates to checkthe tooth from the base circle outwardly to the crown thereof. If the tooth is of true involute form no movement of the indicating arm will occur while any inaccuracies will be recorded. The principle ofthe checking follows the rack principle of constructing involute forms of teeth which is the simplest and most correct method for laying out involute teeth forms onl the circular gears.

As pointed out hereinabove, when the gear is provided with teeth disposed at an angie to the indicating device, the cylinder 51 is rotated in the securing housing 58 Vcorresponding to the lead of the thread so that the stylus will operate along a line normal to the axis of the tooth. In this manner any type of tooth, whether on spur or 25 Thescrew 13 is spiral gears or the thread of a worm may have the involute form thereof checked accurately by the machine. For removing and mounting the shaft 1|, a handle 14 is provided which advances or retracts the center .23 which may be clamped in position by a clampinghandle 15.

While I have described and illustrated but a single embodiment of my invention, it will be apparent to those`skilled in the art that various changes, omissions, additions and substitutions may be made therein without departing from the spirit and scope of my invention as set forth in the accompanying claims.v

I claim'as my invention:

l. An involute testing device including, in com-4 binaticn, a base, a longitudinally. movable table thereon; a rotatable element embodying at least a portion of a master base circle with which a gear lto be tested is mounted concentric thereto androtatable therewith, a carriage movable parallel to a tangent to an arc of said base circle, an indicating device mounted on said carriage, anv element on the device engaging the tooth of a gear to be tested disposed on the base circle of the gear, and means for synchronizing the move- -direction parallel to a tangent to said master base circle, an indicating device carried by said carriage having the contacting point thereof disposed on the base circle of the gear to be tested, means for rotating the element and moving the table in synchronism with each other, and means for adjusting the degree of rotation of the elelment relative to the movement'of said carriage.

3. An involute testing xture including, in combination, a base, a table and carriage on said base movable at right angles to each other, a sine-bar carried by said table and engaged by said carriage, an element rotatable by said table embodying at least a portion of a master base circle with which a gear to be tested is concentrically mounted, means for adjusting said sinebar to have the relative movements between the table and carriage bear the same relation as the radius of the master arc of the base circle bears to that of the base circle of the gear to be tested, and indicatingmeans carried by said carriage and engaging the surface of a toothl of the gear to be checked.

4. A device for checking the involute form of a tooth which includes, in combination, a base, a table mountable on said be for movement thereon, an element embodying at least a portion of a master base circle rotatable by the movement of said table, a sine-bar carried by said table, a carriage movable at an angle to said rst carriage having a portion contacting the sine-bar, an indicating device which is'adjustable parallel with and at right angles to-said carriage, a contacting element on said device which is adjustable'to be positioned on the base circle of a gear to be `checked and which is movable into a position to contact eitherside of a. tooth thereof, means for moving said table to effect the rotation of the element and the gear and for moving the table in ysynchronism therewith to check the accuracy of'the involute form on the tooth.

5. A device for checking the form of the teeth of a helical gear which includes, in combination,

a base, a movable table thereon, an element embodying at least'a portion of a master base circle movable thereby, an indicating device movable by said table parallel to a tangent to said circle, and means for adjusting the indicating deviceto a position corresponding to the helix angle of the teeth of the gear to be tested.

6. A checking device for a gear comprising a supporting member for supporting a gear to be tested; an indicating device and a carrier therefor movable in a direction parallel to a tangent to the base circle of the gear being tested, means operable to effect movement of said carrier and relative rotation between said supporting member and said carrier; and means for adjusting said operable means to vary the rate ratio between said movement and said relative rotation.

'7. A checking device for a gear comprising an angularly -movable base circle member; an indicating device and a carrier therefor movable in a direction parallel to a tangent to said base circle member, operating'means for moving said member and said carrier in synchronized rela# tion; and means connecting said operating means to said member and to said carrier and adjustable to vary the rate ratio between said linear and angular movements.

.8. Ak checking device for a gear comprising supporting means for 'supporting a gear to betested for angular movement about its axis;'an indicating device and' a carrier therefor movable in a direction parallel to a tangent to the base circle of the gear being tested, means operable to linearly move said carrier and angularly .move said supporting means in 'timed relation; and means for adjusting said operable means to vary the rate ratio between said linear and angular movements.

9'. A checking device for a gear comprising sup-.

porting means for supporting a gear to be tested for angular movement about its axis; an indicating device and a carrier therefor movable in a direction parallel to a tangent to the base circie of the gear being tested, a movable operating and angular movements.

p HARRY PELPHREY.

tions to vary the rate ratio between said linear 

